Thermoplastic resins can have improved properties such as lower specific gravity than glass or metal and improved formability, impact resistance, and the like. Recently, thermoplastic resins have been used to manufacture plastic products, as various products such as electric/electronic products have become less expensive and become larger and lighter, and the plastic products have rapidly replaced conventional glass or metal products and been widely used from electric/electronic products to auto parts.
With regard to auto parts, there has been a demand for an unpainted material that is light weight to save energy and also environmentally-friendly. Accordingly, a product manufactured by reinforcing a crystalline resin for example polypropylene with a filler has been developed. Although a filled polypropylene material can be inexpensive and low weight, there can be problems associated with the same. For example, the paint can deteriorate and/or delaminate, resulting in defects and requiring additional processing steps. As another example, a nylon material has a high moisture absorption rate and thus may cause a large dimension change of a product depending on temperature and humidity, which can result in a high defect rate.
Accordingly, there is a need for a thermoplastic resin composition having excellent dimensional stability as well as a good appearance, high impact resistance, and a high strength appropriate for an exterior material capable, for example, of replacing a metal in an automobile.